The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some of such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
With the ever increasing demand for increasing data rates and higher quality services in the world of mobile communications comes ever increasing demand for better performance of cellular network infrastructures. The available frequency resources are limited and need for efficient use of the resources is essential.
It may be difficult to improve spectrum efficiency using traditional solutions. Thus, operators, network and device manufacturers and other players in the field are considering the utilization of unlicensed frequency bands along with costly licensed spectrum. The unlicensed frequency bands are only lightly regulated; users do not need licenses to exploit them. Recently the coexistence of cellular systems such as LTE (long term evolution) along with other radio technologies such as Wi-Fi has been investigated. The purpose is to find a solution which enhances LTE to enable access to unlicensed spectrum while coexisting with other technologies and fulfilling the regulatory requirements.